The present invention relates to UV curable compositions based on the use of C.sub.(8-28) .alpha.-olefin oxide and certain aryl onium salts. More particularly, the present invention relates to paper products treated with a non-transferable paper release coating useful in pressure sensitive adhesive applications.
Prior to the present invention, paper release compositions were often based on the use of heat cured platinum catalyzed organo polysiloxane compositions, as shown for example by Takamizawa et al, U.S. Pat. No. 4,057,596, or an organic solvent containing silicone mixture utilizing a tetra-alkyl titanate curing agent, as taught by Doss et al, U.S. Pat. No. 4,151,344. Although silicones often provide valuable adhesive surfaces on various substrates with excellent mechanical properties, silicones are frequently economically less attractive than the more readily available organics. However, organic coatings in many instances do not possess low enough surface energy to provide good release properties, as shown by a tendency to rub off and to migrate to the surface of the adhesive, as compared to silicone release coatings.
The present invention is based on the discovery that UV curable compositions of C.sub.(8-28) .alpha.-olefin oxides, which optionally can be utilized with polyfunctional epoxides, will provide superior UV curable paper coating compositions when used with an effective amount of an aryl onium salt of the formula, EQU [Y].sup.+ [MQ.sub.n ].sup.-,
where Y is a member selected from EQU [(R).sub.a (R.sup.1).sub.b I] and EQU [(R).sub.c (R.sup.2).sub.d (R.sup.3).sub.e S],
R is a monovalent C.sub.(6-13) aromatic organic radical, R.sup.1 is a divalent aromatic organic radical, R.sup.2 is a monovalent organic aliphatic radical selected from alkyl, cyclo alkyl and substituted alkyl, R.sup.3 is a polyvalent aromatic organic radical forming a heterocyclic or fused ring structure, M is a metal or metalloid, Q is a halogen radical, a is a whole number equal to 0 or 2, b is a whole number equal to 0 to 1 and the sum of a+b is equal to 1 or 2, c is a whole number equal to 0 to 3 inclusive, d is a whole number equal to 0 or 1, e is a whole number equal to 0 or 1, and the sum of c, d, and e is equal to 1 to 3 inclusive, and n is an integer equal to 4-6 inclusive.